Signal receiving apparatus and signal processing method thereof

ABSTRACT

Disclosed herein are a signal receiving apparatus capable of improving signal compensation performance and a signal processing method thereof. The signal receiving apparatus includes a terminal configured to receive a signal from an external device; and an equalizer configured to reduce inter-symbol interference of the signal received through the terminal. A swing level of an output signal output from the equalizer is maintained in a preset range.

CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. § 119(a), this application claims the benefit ofearlier filing date and right of priority to Korean Patent ApplicationNos. 10-2020-0092515, filed on Jul. 24, 2020 and 10-2020-0145482, filedon Nov. 3, 2020, the contents of which are hereby incorporated byreference herein in its entirety.

BACKGROUND

The present disclosure relates to a signal receiving apparatus and asignal processing method thereof.

More specifically, the present disclosure relates to a signal receivingapparatus including at least one equalizer and a signal processingmethod thereof.

A high definition multimedia interface (HDMI) is one of an uncompresseddigital video/audio interface standards. The HDMI transmitshigh-definition multimedia information as high-frequency signal, whichmay cause problems such as noise or signal leakage. In particular, asHDMI 2.1 (or higher) is supported, the frequency increases. In addition,as signal transmission through a longer cable is expected, signalattenuation is expected to be more severe. Therefore, the role of anequalizer of a signal receiving apparatus is becoming more important.

SUMMARY

An object of the present disclosure devised to solve the problem lies ina signal receiving apparatus capable of improving signal compensationperformance of an equalizer, and a signal processing method thereof.

An object of the present disclosure devised to solve the problem lies ina signal receiving apparatus for implementing automatic gain control(AGC) in an equalizer, and a signal processing method thereof.

A signal receiving apparatus according to an embodiment of the presentdisclosure comprises a terminal configured to receive a signal from anexternal device; and an equalizer configured to reduce inter-symbolinterference of the signal received through the terminal, wherein aswing level of an output signal output from the equalizer is maintainedin a preset range.

The equalizer comprises a first equalizer configured to amplify thesignal received through the terminal and a second equalizer configuredto reduce inter-symbol interference in a signal output from the firstequalizer, and wherein a swing level of the signal output from the firstequalizer to the second equalizer falls within the preset range.

The signal receiving apparatus further comprises a processor configuredto adjust the swing level of the output signal.

The signal receiving apparatus further comprises a detector configuredto detect the swing level of the output signal, wherein the processor isconfigured to adjust the swing level of the output signal such that theswing level of the output signal falls within the preset range based ona result of detection of the detector.

The processor is configured to determine DC gain of the first equalizerfor enabling the swing level of the output signal to fall within thepreset range.

The processor is configured to determine the DC gain by stepwisechanging the DC gain until the swing level of the output signal fallswithin the preset range.

When the DC gain is determined, the processor is configured to determineAC gain by detecting an error rate of the output signal with respect tothe determined DC gain.

The equalizer compensates for the signal received through the terminalaccording to the determined DC gain and the AC gain.

The first equalizer is a continuous time linear equalizer (CTLE), andthe second equalizer is a decision feedback equalizer (DFE).

A signal processing method of a signal receiving apparatus according toan embodiment of the present disclosure comprises receiving a signalfrom an external device; and performing signal processing to reduceinter-symbol interference of the received signal through an equalizer,wherein a swing level of an output signal output from the equalizer ismaintained in a preset range.

The performing of signal processing comprises: by a first equalizer,amplifying the received signal; and by a second equalizer, reducinginter-symbol interference in a signal output from the first equalizer,wherein a swing level of the signal output from the first equalizer tothe second equalizer falls within the preset range.

The signal processing method further comprises adjusting the swing levelof the output signal such that the swing level of the output signalfalls within the preset range.

The signal processing method further comprises determining DC gain ofthe first equalizer for enabling the swing level of the output signal tofall within the preset range.

The determining of the DC gain comprises determining the DC gain bystepwise changing the DC gain until the swing level of the output signalfalls within the preset range.

The signal processing method further comprises when the DC gain isdetermined, determining AC gain by detecting an error rate of the outputsignal with respect to the determined DC gain.

According to the present disclosure, since operation stability of anequalizer is secured and performance is improved, inter-symbolinterference is further reduced.

According to the present disclosure, since adaptive equalizer gainadjustment is possible with respect to an input signal, it is possibleto maximize compensation efficiency of signals received through variouscables and various signal transmitting apparatuses.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing a state in which a signal receivingapparatus according to an embodiment of the present disclosure receivesa signal through a high definition multimedia interface (HDMI).

FIG. 2 is a block diagram showing the configuration of the signalreceiving apparatus of FIG. 1.

FIG. 3 is a view showing the physical layer of the external deviceinterface shown in FIG. 2.

FIG. 4 is a view showing the physical layer of an external deviceinterface according to an embodiment of the present disclosure.

FIG. 5 is a circuit diagram of a continuous time linear equalizer(CTLE).

FIG. 6 is a flowchart illustrating a method of operating a signalreceiving apparatus according to an embodiment of the presentdisclosure.

FIG. 7 is a view showing a state in which the swing level of the signaloutput from the CTLE according to the embodiment of the presentdisclosure is adjusted.

FIG. 8 shows eye diagrams of a signal output from a conventional signalprocessing apparatus and a signal output from a signal processingapparatus according to an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, the present invention will be described in detail withreference to the drawings.

The suffixes “module” and “unit” for components used in the descriptionbelow are assigned or mixed in consideration of easiness in writing thespecification and do not have distinctive meanings or roles bythemselves.

FIG. 1 is a schematic view showing a state in which a signal receivingapparatus according to an embodiment of the present disclosure receivesa signal through a high definition multimedia interface (HDMI).

As shown in FIG. 1, the signal receiving apparatus 10 may be connectedto an external device 20 through an interface 1 to receive avideo/audio/control signal from the external device 20.

Here, the interface 1 may be a high definition multimedia interface(HDMI), but this is merely an example and is not limited thereto. In thepresent disclosure, for convenience of description, it is assumed thatthe interface 1 is an HDMI.

The signal receiving apparatus 10 includes a terminal 10 a connectedwith the HDMI 1, and the terminal 10 a may receive the signal of theexternal device 20 through the HDMI 1. The terminal 10 a may be an HDMIterminal. Similarly, the external device 20 may include a terminal 20 aconnected with the HDMI 1, and the terminal 20 a may transmit a signalto the HDMI 1.

The HDMI 1 may include a pair of connectors 1 a and 1 b and an HDMIcable 1 c located between the pair of connectors 1 a and 1 b. The HDMIcable 1 c may include signal lines for signal transmission between thepair of connectors 1 a and 1 b, and the connectors 1 a and 1 b may beterminals for connection to a sink apparatus or a source apparatus.

The signal receiving apparatus 10 may be a sink apparatus, and the sinkapparatus may include all types of apparatuses capable of receiving andreproducing signals (e.g., HDMI signals) from a source apparatus. Forexample, the sink apparatus may be implemented as various apparatusessuch as a TV, a computer, a DVD player, a cellular phone, a smartphone,a personal digital assistant (PDA), a laptop PC, a tablet PC, anelectronic book, an electronic picture frame, a kiosk, etc.

The external device 20 may be a source apparatus and includes all typesof apparatus capable of generating and transmitting signals (e.g., HDMIsignals). For example, the external device 20 may be implemented asvarious apparatuses such as a TV, a computer, a DVD player, a cellularphone, a smartphone, a personal digital assistant (PDA), a laptop PC, atablet PC, an electronic book, an electronic picture frame, a kiosk, aBlu-ray disc, a set-top box, etc.

FIG. 2 is a block diagram showing the configuration of the signalreceiving apparatus of FIG. 1.

The signal receiving apparatus 10 may be a display apparatus 100described below or a component configuring the display apparatus 100. Inthe present disclosure, it is assumed that the signal receivingapparatus 10 is the display apparatus 100 described below.

Meanwhile, the signal receiving apparatus 10 may include some or all ofthe components shown in FIG. 2. That is, FIG. 2 shows only an example ofdescribing the configuration of the signal receiving apparatus 10, andthe configuration of the signal receiving apparatus 10 may be various.

Referring to FIG. 2, a display device 100 can include a broadcastreceiver 130, an external device interface 135, a storage 140, a userinput interface 150, a controller 170, a wireless communicationinterface 173, a display 180, an audio output interface 185, and a powersupply 190.

The broadcast receiver 130 can include a tuner 131, a demodulator 132,and a network interface 133.

The tuner 131 can select a specific broadcast channel according to achannel selection command. The tuner 131 can receive broadcast signalsfor the selected specific broadcast channel.

The demodulator 132 can divide the received broadcast signals into videosignals, audio signals, and broadcast program related data signals andrestore the divided video signals, audio signals, and data signals to anoutput available form.

The network interface 133 can provide an interface for connecting thedisplay device 100 to a wired/wireless network including internetnetwork. The network interface 133 can transmit or receive data to orfrom another user or another electronic device through an accessednetwork or another network linked to the accessed network.

The network interface 133 can access a predetermined webpage through anaccessed network or another network linked to the accessed network. Thatis, it can transmit or receive data to or from a corresponding server byaccessing a predetermined webpage through network.

Then, the network interface 133 can receive contents or data providedfrom a content provider or a network operator. That is, the networkinterface 133 can receive contents such as movies, advertisements,games, VODs, and broadcast signals, which are provided from a contentprovider or a network provider, through network and information relatingthereto.

Additionally, the network interface 133 can receive firmware updateinformation and update files provided from a network operator andtransmit data to an internet or content provider or a network operator.

The network interface 133 can select and receive a desired applicationamong applications open to the air, through network.

The external device interface 135 can receive an application or anapplication list in an adjacent external device and deliver it to thecontroller 170 or the storage 140.

The external device interface 135 can provide a connection path betweenthe display device 100 and an external device. The external deviceinterface 135 can receive at least one of image and audio outputted froman external device that is wirelessly or wiredly connected to thedisplay device 100 and deliver it to the controller. The external deviceinterface 135 can include a plurality of external input terminals. Theplurality of external input terminals can include an RGB terminal, atleast one High Definition Multimedia Interface (HDMI) terminal, and acomponent terminal.

An image signal of an external device inputted through the externaldevice interface 135 can be outputted through the display 180. A soundsignal of an external device inputted through the external deviceinterface 135 can be outputted through the audio output interface 185.

An external device connectable to the external device interface 135 canbe one of a set-top box, a Blu-ray player, a DVD player, a game console,a sound bar, a smartphone, a PC, a USB Memory, and a home theater systembut this is just exemplary.

Additionally, some content data stored in the display device 100 can betransmitted to a user or an electronic device, which is selected fromother users or other electronic devices pre-registered in the displaydevice 100.

The storage 140 can store signal-processed image, voice, or data signalsstored by a program in order for each signal processing and control inthe controller 170.

Additionally, the storage 140 can perform a function for temporarilystore image, voice, or data signals outputted from the external deviceinterface 135 or the network interface 133 and can store information ona predetermined image through a channel memory function.

The storage 140 can store an application or an application list inputtedfrom the external device interface 135 or the network interface 133.

The display device 100 can play content files (for example, video files,still image files, music files, document files, application files, andso on) stored in the storage 140 and provide them to a user.

The user input interface 150 can deliver signals inputted from a user tothe controller 170 or deliver signals from the controller 170 to a user.For example, the user input interface 150 can receive or process controlsignals such as power on/off, channel selection, and screen setting fromthe remote controller 200 or transmit control signals from thecontroller 170 to the remote controller 200 according to variouscommunication methods such as Bluetooth, Ultra Wideband (WB), ZigBee,Radio Frequency (RF), and IR.

Additionally, the user input interface 150 can deliver, to thecontroller 170, control signals inputted from local keys (not shown)such as a power key, a channel key, a volume key, and a setting key.

Image signals that are image-processed in the controller 170 can beinputted to the display 180 and displayed as an image corresponding tocorresponding image signals. Additionally, image signals that areimage-processed in the controller 170 can be inputted to an externaloutput device through the external device interface 135.

Voice signals processed in the controller 170 can be outputted to theaudio output interface 185. Additionally, voice signals processed in thecontroller 170 can be inputted to an external output device through theexternal device interface 135.

Besides that, the controller 170 can control overall operations in thedisplay device 100.

Additionally, the controller 170 can control the display device 100 by auser command or internal program inputted through the user inputinterface 150 and download a desired application or application listinto the display device 100 in access to network.

The controller 170 can output channel information selected by a usertogether with processed image or voice signals through the display 180or the audio output interface 185.

Additionally, according to an external device image playback commandreceived through the user input interface 150, the controller 170 canoutput image signals or voice signals of an external device such as acamera or a camcorder, which are inputted through the external deviceinterface 135, through the display 180 or the audio output interface185.

Moreover, the controller 170 can control the display 180 to displayimages and control broadcast images inputted through the tuner 131,external input images inputted through the external device interface135, images inputted through the network interface, or images stored inthe storage 140 to be displayed on the display 180. In this case, animage displayed on the display 180 can be a still image or video andalso can be a 2D image or a 3D image.

Additionally, the controller 170 can play content stored in the displaydevice 100, received broadcast content, and external input contentinputted from the outside, and the content can be in various formatssuch as broadcast images, external input images, audio files, stillimages, accessed web screens, and document files.

Moreover, the wireless communication interface 173 can perform a wiredor wireless communication with an external electronic device. Thewireless communication interface 173 can perform short-rangecommunication with an external device. For this, the wirelesscommunication interface 173 can support short-range communication byusing at least one of Bluetooth™, Radio Frequency Identification (RFID),Infrared Data Association (IrDA), Ultra Wideband (UWB), ZigBee, NearField Communication (NFC), Wireless-Fidelity (Wi-Fi), Wi-Fi Direct, andWireless Universal Serial Bus (USB) technologies. The wirelesscommunication interface 173 can support wireless communication betweenthe display device 100 and a wireless communication system, between thedisplay device 100 and another display device 100, or between networksincluding the display device 100 and another display device 100 (or anexternal server) through wireless area networks. The wireless areanetworks can be wireless personal area networks.

Herein, the other display device 100 can be a mobile terminal such as awearable device (for example, a smart watch, a smart glass, and a headmounted display (HMD)) or a smartphone, which is capable of exchangingdata (or inter-working) with the display device 100. The wirelesscommunication interface 173 can detect (or recognize) a communicablewearable device around the display device 100. Furthermore, if thedetected wearable device is a device authenticated to communicate withthe display device 100, the controller 170 can transmit at least part ofdata processed in the display device 100 to the wearable device throughthe wireless communication interface 173. Accordingly, a user of thewearable device can use the data processed in the display device 100through the wearable device.

The display 180 can convert image signals, data signals, or OSD signals,which are processed in the controller 170, or images signals or datasignals, which are received in the external device interface 135, intoR, G, and B signals to generate driving signals.

Furthermore, the display device 100 shown in FIG. 2 is just oneembodiment of the present invention and thus, some of the componentsshown can be integrated, added, or omitted according to thespecification of the actually implemented display device 100.

That is, if necessary, two or more components can be integrated into onecomponent or one component can be divided into two or more componentsand configured. Additionally, a function performed by each block is todescribe an embodiment of the present invention and its specificoperation or device does not limit the scope of the present invention.

According to another embodiment of the present invention, unlike FIG. 2,the display device 100 can receive images through the network interface133 or the external device interface 135 and play them without includingthe tuner 131 and the demodulator 132.

For example, the display device 100 can be divided into an imageprocessing device such as a set-top box for receiving broadcast signalsor contents according to various network services and a content playbackdevice for playing contents inputted from the image processing device.

In this case, an operating method of a display device according to anembodiment of the present invention described below can be performed byone of the display device described with reference to FIG. 2, an imageprocessing device such as the separated set-top box, and a contentplayback device including the display 180 and the audio output interface185.

The audio output interface 185 receives the audio processed signal fromthe controller 170 and outputs the sound.

The power supply 190 supplies the corresponding power throughout thedisplay device 100. In particular, the power supply 190 supplies powerto the controller 170 that can be implemented in the form of a System OnChip (SOC), a display 180 for displaying an image, and the audio outputinterface 185 for outputting audio or the like.

Specifically, the power supply 190 may include a converter forconverting an AC power source into a DC power source, and a dc/dcconverter for converting a level of the DC source power.

The remote controller 200 transmits a user input to the user inputinterface 150. To this end, the remote controller 200 may use Bluetooth,radio frequency (RF) communication, infrared (IR) communication, ultrawideband (UWB), ZigBee, or the like. In addition, the remote controller200 may receive video, audio, or data signal output from the user inputinterface 150 and display the video, audio, or data signal or outputsound.

FIG. 3 is a view showing the physical layer of the external deviceinterface shown in FIG. 2.

The external device interface 135 of the signal receiving apparatus 10may be an HDMI interface, but this is merely an example and is notlimited thereto. In the present disclosure, it is assumed that theexternal device interface 135 is an HDMI interface, but this is only forconvenience of description.

The physical layer of the HDMI interface may include at least oneequalizer. Here, the equalizer may reinforce or cut the received signal,thereby reducing a jitter phenomenon wherein some aspects of a wave aredeviated or displaced at a high frequency.

As shown in FIG. 3, the HDMI interface includes a first equalizer and asecond equalizer. The first equalizer may be a signal amplificationlinear equalizer and the second equalizer may be a non-linear equalizerfor eliminating non-amplification bit interference (inter-symbolinterference (ISI)). For example, the first equalizer may be acontinuous time linear equalizer (CTLE) and the second equalizer may bea decision feedback equalizer (DFE), but this is only an example and isnot limited thereto.

The CTLE may amplify a signal to adjust all frequency components of aninput signal to a similar magnitude, thereby improving eye diagramperformance.

The DFE may be a circuit for improving BER performance by eliminatinginter-symbol interference of an input signal using a feedback filter.The DFE may compensate for a signal without amplifying a noise level.

When an HDMI is connected to an HDMI terminal, the CTLE may receive thesignal of the external device through the HDMI terminal. That is, theCTLE may receive the signal of the external device received by the HDMIterminal, process the signal input through the HDMI terminal accordingto equalizer gain, and output the processed signal to the DFE.

The DFE may reduce inter-symbol interference by compensating for asignal through a subtraction operation between a signal output from theCTLE and a DFE variable ((3, ISI term). At this time, the DFE variableis a feedback signal determined by an internal operation logic and isaffected by a signal input to the DFE, that is, a signal output from theCTLE. That is, the signal output from the CTLE to the DFE may determinethe DFE variable and affect the DFE logic. Accordingly, when themagnitude of the signal output from the CTLE to the DFE is out of theallowable voltage range of a digital-to-analog converter (DAC) in theDFE, the DFE variable may not be properly calculated and thus signalcompensation may not be optimally performed. Accordingly, the magnitudeof the signal output from the CTLE to the DFE shall be smaller than theallowable voltage range of the DAC. That is, there may be a need for amethod of performing control such that the magnitude of the signaloutput from the CTLE to the DFE falls within the allowable voltage rangeof the DAC.

FIG. 4 is a view showing the physical layer of an external deviceinterface according to an embodiment of the present disclosure.

The external device interface 135 of the signal receiving apparatus 10according to the embodiment of the present disclosure may be an HDMIinterface, but this is only an example and is not limited thereto. Inthe present disclosure, it is assumed that the external device interface135 is an HDMI interface, but this is only for convenience ofdescription.

As shown in FIG. 4, the physical layer of the HDMI interface may includeat least some or all of one or more equalizers 12 and 14, a detector 16and a processor 18.

The equalizers 12 and 14 may reduce inter-symbol interference of thesignal received through the HDMI terminal.

The detector 16 may detect the swing level of an output signal outputfrom the first equalizer 12 to the second equalizer 14.

The processor 18 may control the equalizers 12 and 14 and the detector16. For example, the processor 18 may adjust the swing level of theoutput signal output from the first equalizer 12 to the second equalizer14.

In particular, according to the present disclosure, the processor 18 maycontrol at least some or all of the equalizers 12 and 14 or the detector16, such that the swing level of the output signal output from theequalizers 12 and 14 is constantly maintained in a preset range.

More specifically, the equalizers 12 and 14 include the first equalizer12 and the second equalizer 14, the first equalizer 12 may be a signalamplification linear equalizer, and the second equalizer 14 may be anon-linear equalizer for eliminating non-amplification bit interference(ISI). For example, the first equalizer 12 may be a continuous timelinear equalizer (CTLE) and the second equalizer 14 may be a decisionfeedback equalizer (DFE), but this is only an example and is not limitedthereto.

The first equalizer 12 may amplify a signal input through a terminal,and the second equalizer 14 may reduce inter-symbol interference in asignal output from the first equalizer 12 to the second equalizer 14. Atthis time, the swing level of the signal output from the first equalizer12 to the second equalizer 14 may fall within a preset range, and thepreset range may include the allowable voltage range of the DAC in thesecond equalizer 14. For example, the preset range may be 800 mV to 1 V,but this is only an example and is not limited thereto.

Meanwhile, the processor 18 may adjust the swing level of the outputsignal output from the first equalizer 12 to the second equalizer 14.That is, the processor 18 may adjust the equalizer gain of the firstequalizer 12 such that the swing level of the output signal output fromthe first equalizer 12 falls within the preset range.

First, the equalizer gain will be described with reference to FIG. 5.

FIG. 5 is a circuit diagram of a continuous time linear equalizer(CTLE).

When the first equalizer 12 is a CTLE as shown in FIG. 5, a transferfunction H(s) and the positions of zero and pole may be calculated asfollows.

${H(s)} = {\frac{g_{m}}{C_{p}}\frac{s + \frac{1}{R_{S}C_{S}}}{\left( {s + \frac{1 + {g_{m}R_{s}\text{/}2}}{R_{S}C_{S}}} \right)\left( {s + \frac{1}{R_{D}C_{p}}} \right)}}$${\omega_{z} = \frac{1}{R_{S}C_{s}}},{\omega_{p\; 1} = \frac{1 + {g_{m}R_{S}\text{/}2}}{R_{S}C_{S}}},{\omega_{p\; 2} = \frac{1}{R_{D}C_{p}}}$

Therefore, DC gain and ideal peak gain may be calculated as follows.

${{{DC}\mspace{14mu}{gain}} = \frac{g_{m}R_{D}}{1 + {g_{m}R_{S}\text{/}2}}},$

Ideal peak gain=g_(m)R_(D)

Accordingly, an ideal peak index may be calculated as follows.

${{Ideal}\mspace{14mu}{Peaking}} = {\frac{{Ideal}\mspace{14mu}{peak}\mspace{14mu}{gain}}{{DC}\mspace{14mu}{gain}} = {\frac{\omega_{p\; 1}}{\omega_{z}} = {1 + {g_{m}R_{S}\text{/}2}}}}$

The resistor and capacitor of the CTLE may be designed as variableelements. As the values of the resistors and the capacitor are adjusted,the positions of the zero and pole are changed and thus equalizer gainmay be adjusted.

Such equalizer gain may include DC gain and AC gain, and signalamplification is determined by the DC gain and the AC gain.

The DC gain is a gain value at a zero frequency in a CTLE transferfunction and may be Rs. The AC gain is a gain value at a peak frequencyin a CTLE transfer function and may be Cs. Rs and Cs may be adjusted bythe operating method of the CTLE.

Accordingly, the processor 18 may first determine DC gain for enablingthe swing level of the signal output from the first equalizer 12 to fallwithin a preset range, by adjusting the DC gain. When the DC gain isdetermined, the AC gain may be determined by performing error profilewhile adjusting the AC gain with respect to the determined DC gain.

To this end, the detector 16 may detect the swing level of the outputsignal output from the first equalizer 12. The processor 18 may adjustthe swing level of the output signal such that the swing level of theoutput signal output from the first equalizer 12 falls within the presetrange based on the result of detection of the detector 16.

When the swing level of the output signal output from the firstequalizer 12 does not fall within the preset range based on the resultof detection of the detector 16, the processor 18 may determine the DCgain by stepwise changing the DC gain until the swing level of theoutput signal falls within the preset range. A series of operations maybe referred to as a DC gain scan function.

Hereinafter, a detailed method will be described with reference to FIG.6.

FIG. 6 is a flowchart illustrating a method of operating a signalreceiving apparatus according to an embodiment of the presentdisclosure.

First, the DC gain and the AC gain may be set to a default DC gain valueand a default AC gain value, respectively. For example, the default DCgain value and the default AC gain value may be respectively 0 dB and 1dB, but this is only an example and is not limited thereto.

The processor 18 may detect the swing level of the output signal outputfrom the first equalizer 12 to the second equalizer 14 (S11).

That is, the processor 18 may detect the swing level of the signalprocessed by the first equalizer 12 through the detector 16.

The processor 18 may determine whether the swing level of the outputsignal falls within the preset range (S13).

That is, the processor 18 may determine whether the swing level of thesignal output from the first equalizer 12 detected by the detector 16falls within the preset range. Here, the preset range may be theallowable voltage range of the DAC in the second equalizer 14. Forexample, the preset range may be 800 mV to 1 V, but this is only anexample and is not limited thereto.

When the swing level of the output signal does not fall within thepreset range (S15), the processor 18 may determine whether the swinglevel of the output signal is less than the preset range (S17).

For example, when the predetermined range is 800 mV to 1V, the processor18 may determine whether the swing level of the output signal is lessthan 800 mV. That is, the processor 18 may determine whether the swinglevel of the output signal is less than a minimum value of the presetrange.

When the swing level of the output signal is less than the preset range,the processor 18 may increase the DC gain value (S19).

For example, the processor 18 may increase the DC gain value by adding areference value (e.g., 0.5 dB) to the current DC gain value. Here, thereference value is only an example and is not limited thereto.

The processor 18 may determine whether the swing level of the outputsignal is included in the preset range after increasing the DC gainvalue (S13).

Meanwhile, when the swing level of the output signal is greater than thepreset range, the processor 18 may decrease the DC gain value (S19).

For example, when the swing level of the output signal is greater than amaximum value of the preset range, the processor 18 may decrease the DCgain value.

For example, the processor 18 may decrease the DC gain value bysubtracting a reference value (e.g., 0.5 dB) from the current DC gainvalue. Here, the reference value is only an example and is not limitedthereto.

The processor 18 may determine whether the swing level of the outputsignal falls within the preset range after decreasing the DC gain value(S13).

When the swing level of the signal output from the first equalizer 12 isgreater than the preset range, the processor 18 may stepwise decreasethe DC gain value until the swing level of the signal output from thefirst equalizer 12 falls within the predetermined range. On thecontrary, when the swing level of the signal output from the firstequalizer 12 is less than the preset range, the processor 18 maystepwise increase the DC gain value until the swing level of the signaloutput from the first equalizer 12 falls within the predetermined range.

That is, the processor 18 may determine the DC gain of the firstequalizer 12 such that the swing level of the output signal falls withinthe preset range.

When the swing level of the signal output from the first equalizer 12falls within the preset range, the processor 18 may determine the DCgain as a current DC gain value (S23).

Therefore, the swing level of the output signal output from the firstequalizer 12 to the second equalizer 14 may fall within the presetrange.

FIG. 7 is a view showing a state in which the swing level of the signaloutput from the CTLE according to the embodiment of the presentdisclosure is adjusted.

As shown in (a) of FIG. 7, when the swing level of the signal input tothe first equalizer 12 is 1 V, the processor 18 may adjust the swinglevel of the signal output from the first equalizer 12 to the secondequalizer 14 to 480 mV, by changing the DC gain.

Alternatively, as shown in (b) of FIG. 7, when the swing level of thesignal input to the first equalizer 12 is 0.1 V, the processor 18 mayadjust the swing level of the signal output from the first equalizer 12to the second equalizer 14 to 480 mV, by changing the DC gain.

That is, the processor 18 may adjust the DC gain such that the swinglevel of the signal output from the first equalizer 12 to the secondequalizer 14 falls within the preset range (or the preset level),regardless of the swing level of the signal input to the first equalizer12.

FIG. 6 will be described again.

When the DC gain is determined, the processor 18 may adjust AC gain withrespect to the determined DC gain (S25).

Specifically, when the DC gain is determined, the processor 18 maydetermine the AC gain by detecting the error rate of the output signalwith respect to the determined DC gain. That is, the processor 18 maydetect the error rate of each AC gain with respect to the determined DCgain, and select AC gain with a lowest error rate. Therefore, theprocessor 18 may acquire AC gain for maximizing the eye open area of theoutput signal.

For example, when the DC gain is determined, the processor 18 may detectthe error rate of each AC gain value while adjusting the AC gain valueand determine an AC gain value having a smallest error rate as AC gain.

Error rate detection may include various methods such as a method ofcounting TMDS (Transition Minimized Differential Signaling) errors, amethod of detecting BCH (Bose, Chaudhri, Hocquenghem Code) or ECC (ErrorCheck and Correct Memory) errors, etc.

The first equalizer 12 may perform signal processing according to the DCgain and AC gain determined by the above-described method.

That is, the equalizers 12 and 14 may compensate for the signal receivedthrough the terminal according to the DC gain and AC gain determinedusing the above-described method.

(a) of FIG. 8 is an eye diagram of a signal output from a conventionalsignal processing apparatus, and (b) of FIG. 8 is an eye diagram of asignal output from a signal processing apparatus according to anembodiment of the present disclosure.

(a) and (b) of FIG. 8 may show the result of measuring signals outputwhen signals having different swing levels (e.g., Signal 1 having aswing level of 1000 mV, Signal 2 having a swing level of 1500 mV andSignal 3 having a swing level of 200 mV) are input to the conventionalsignal receiving apparatus and the signal receiving apparatus accordingto the embodiment of the present disclosure. That is, (a) and (b) ofFIG. 8 may show results of measuring wavelengths through equipments(e.g., a CTS test equipment and a generator) on a PCB pattern.

Since the equalizer of the conventional signal receiving apparatus doesnot separately adjust DC gain, an input signal is processed according topredetermined DC gain and thus the change width of the swing level ofthe signal output from the signal processing apparatus may be large asshown in (a) of FIG. 8. Referring to the detailed example shown in (a)of FIG. 8, the swing level of Signal 1 may be less than VDAC (theallowable voltage range of the digital-to-analog converter (DAC)), theswing level of Signal 2 may be equal to VDAC, and the swing level ofSignal 3 may be greater than VDAC. In this case, signal compensationperformance of the signal processing apparatus for Signal 1 and Signal 3is lower than signal compensation performance of the signal processingapparatus for Signal 2. Therefore, it may be difficult to restorerequired signal quality.

Meanwhile, since the equalizer of the signal apparatus according to theembodiment of the present disclosure adjusts the swing level of theoutput signal to be included in VDAC by adjusting DC gain according tothe swing level of the input signal, as shown in (b) of FIG. 8, theswing levels of the output signals may be constantly maintained in theVDAC range (e.g., 800 mV to 1 V). Accordingly, the signal processingapparatus according to the present disclosure is advantageous in thatsignal compensation performance is guaranteed regardless of the swinglevel of the input signal and required signal quality can be restored.

Accordingly, the signal apparatus according to the present disclosurehas an advantage of improving responsiveness to various source apparatusand various cables. That is, according to the present disclosure,flexible signal process is possible regardless of the magnitude of thesignal transmitted from the source apparatus or the length of the cable.

According to the present disclosure, since operation stability of anequalizer is secured and performance is improved, inter-symbolinterference is further reduced.

According to the present disclosure, since adaptive equalizer gainadjustment is possible with respect to an input signal, it is possibleto maximize compensation efficiency of signals received through variouscables and various signal transmitting apparatuses.

The present disclosure may be embodied as computer-readable codes on aprogram-recorded medium. The computer-readable recording medium may beany recording medium that stores data which can be thereafter read by acomputer system. Examples of the computer-readable medium may includehard disk drive (HDD), solid state disk (SSD), silicon disk drive (SDD),read-only memory (ROM), random-access memory (RAM), CD-ROM, a magnetictape, a floppy disk, and an optical data storage device. In addition,the computer may include the controller 170 of the display device 100.Accordingly, the above detailed description should not be construed asbeing restrictive in all respects and should be considered illustrative.The scope of the present specification should be determined by rationalinterpretation of the appended claims, and all changes within theequivalent scope of the present specification fall within the scope ofthe present specification.

The above description is merely illustrative of the technical idea ofthe present invention, and various modifications and changes may be madethereto by those skilled in the art without departing from the essentialcharacteristics of the present invention.

Therefore, the embodiments of the present invention are not intended tolimit the technical spirit of the present invention but to illustratethe technical idea of the present invention, and the technical spirit ofthe present invention is not limited by these embodiments.

The scope of protection of the present invention should be interpretedby the appending claims, and all technical ideas within the scope ofequivalents should be construed as falling within the scope of thepresent invention.

What is claimed is:
 1. A signal receiving apparatus comprising: aterminal configured to receive a signal from an external device; and anequalizer configured to reduce inter-symbol interference of the signalreceived through the terminal, wherein a swing level of an output signaloutput from the equalizer is maintained in a preset range.
 2. The signalreceiving apparatus of claim 1, wherein the equalizer comprises a firstequalizer configured to amplify the signal received through the terminaland a second equalizer configured to reduce inter-symbol interference ina signal output from the first equalizer, and wherein a swing level ofthe signal output from the first equalizer to the second equalizer fallswithin the preset range.
 3. The signal receiving apparatus of claim 1,further comprising a processor configured to adjust the swing level ofthe output signal.
 4. The signal receiving apparatus of claim 3, furthercomprising a detector configured to detect the swing level of the outputsignal, wherein the processor is configured to adjust the swing level ofthe output signal such that the swing level of the output signal fallswithin the preset range based on a result of detection of the detector.5. The signal receiving apparatus of claim 3, wherein the processor isconfigured to determine DC gain of the first equalizer for enabling theswing level of the output signal to fall within the preset range.
 6. Thesignal receiving apparatus of claim 5, wherein the processor isconfigured to determine the DC gain by stepwise changing the DC gainuntil the swing level of the output signal falls within the presetrange.
 7. The signal receiving apparatus of claim 5, wherein, when theDC gain is determined, the processor is configured to determine AC gainby detecting an error rate of the output signal with respect to thedetermined DC gain.
 8. The signal receiving apparatus of claim 7,wherein the equalizer compensates for the signal received through theterminal according to the determined DC gain and the AC gain.
 9. Thesignal receiving apparatus of claim 2, wherein the first equalizer is acontinuous time linear equalizer (CTLE), and wherein the secondequalizer is a decision feedback equalizer (DFE).
 10. A signalprocessing method of a signal receiving apparatus, the signal processingmethod comprising: receiving a signal from an external device; andperforming signal processing to reduce inter-symbol interference of thereceived signal through an equalizer, wherein a swing level of an outputsignal output from the equalizer is maintained in a preset range. 11.The signal processing method of claim 10, wherein the performing ofsignal processing comprises: by a first equalizer, amplifying thereceived signal; and by a second equalizer, reducing inter-symbolinterference in a signal output from the first equalizer, wherein aswing level of the signal output from the first equalizer to the secondequalizer falls within the preset range.
 12. The signal processingmethod of claim 11, further adjusting the swing level of the outputsignal such that the swing level of the output signal falls within thepreset range.
 13. The signal processing method of claim 12, furthercomprising determining DC gain of the first equalizer for enabling theswing level of the output signal to fall within the preset range. 14.The signal processing method of claim 13, wherein the determining of theDC gain comprises determining the DC gain by stepwise changing the DCgain until the swing level of the output signal falls within the presetrange.
 15. The signal processing method of claim 13, further comprising,when the DC gain is determined, determining AC gain by detecting anerror rate of the output signal with respect to the determined DC gain.